In a large scale integrated circuits, metal-oxide-semiconductor field effect transistors or MOSFETS are integrated in a monolithic semiconductor substrate. The design and fabrication of a large scale integrated circuit is time consuming and costly. For cost-effectiveness, it is customary to simulate the circuit design with computer-aided analysis. How well the simulation can predict the performance depends on the accuracy of the models used in the simulation program. Since MOSFETS constitute the bulk of large scale integrated circuits, accurate modeling of the MOSFETS is the key in any simulation program.
In large scale integration, the channel length of MOSFET is scaled down to permit higher packing density. For short channel MOSFETs, the conventional one-dimensional analysis is not adequate to calculate the current voltage characteristics because of two-dimensional charge sharing effect at the source and drain junctions. Two-dimensional solution of the Poisson's equation is difficult to obtain analytically. Most investigators resort to numerical methods to attack the problem. Unfortunately, the progress is long and tedious, and impractical to be incorporated in a circuit analysis program. This invention presents a speedy method to simulate the characteristics of a short channel MOSFET, taking into account the two-dimensional effects.